Part 5 (1/2)

_Fig. 1_ shows a home-made microscope ready for use. It will be seen that the main part consists of a wooden box having a hole in the top and open in front. To the back is attached a cork by means of a piece of thin metal as shown in _fig. 2_. Through this cord slides a rod on which slides another cork. A piece of bra.s.s wire has one end wound round the upper cork while the other end projects as an arm at right angles to the rod, and this projecting end sharpened and upturned, pa.s.ses through holes drilled in the handle of the magnifier, and thus supports it. The lenses are focused, _i. e._ brought to the right distance from the object viewed, by sliding the cork up and down on the rod.

[Ill.u.s.tration: FIG. 1.]

The object rests on a piece of gla.s.s laid over the hole in the top of the box. A piece of wood covered with white paper and placed below the object at an angle of about forty-five degrees answers for a reflector to illuminate those objects through which the light can pa.s.s. The pure white surface is better for the purpose than a mirror.

[Ill.u.s.tration: FIG. 2.]

The most delicate part of the construction is making the holes in the corks for the rod to slide through. This may be done perfectly, however, by making the holes with a rat-tail file, trying the rod now and then until it moves just right. The best thing for the rod is a piece of bra.s.s wire one quarter of an inch thick; a lead pencil however is a good subst.i.tute. Before bending the end of the bra.s.s wire arm it is well to heat it red-hot at the point of bending, to take out the temper: as otherwise it may break. The holes in the handle of the magnifier should be drilled as near the front as possible and so arranged that when the magnifier is in position the smallest lens will be near the object.

[Ill.u.s.tration: FIG. 3.]

The mounted needles are shown in _fig. 3_. One pair of each kind will be enough to start with. To make one, take a fine needle, break off about a third, so it will not be too long and springy; then with a pair of pincers force it into the handle point first, withdraw it and finally force it in again with the point out. It may be easily bent with the pincers by first heating it to redness in a flame. When bent, heat it red once more and plunge quickly into water to re-temper it. Rubbing on an oil stone may be necessary to remove roughness. Should the handles show any tendency to split, it would be well to wrap the end tightly with waxed thread.

The forceps (_fig. 4_) may be purchased either of bra.s.s or steel at no great expense. Although not necessary it is more convenient to have them curved than straight.

[Ill.u.s.tration: FIG. 4.]

If the reader will carefully follow the directions given below and endeavor to see for himself all the parts spoken of, he will probably have very little difficulty afterward in the use of the instruments just described; and the enjoyment he will have when he has learned how to examine little things, will amply repay for careful and persistent efforts at the start. Get a Dandelion in full bloom and also one that has gone to seed.

Have the microscope and the other instruments ready for use. The best place to work is on a table in front of a window where there is plenty of light, but not the direct rays of the sun.

Now cut the blossom in halves from the stem up. It will be seen that the stem is hollow and ends above in a cus.h.i.+on-like expansion. From the upper surface of this grow a number of little flowers, while from the sides there sprang two rows of little green organs that enclose the flower cl.u.s.ter like a cup. Remove one of the flowers with the forceps and place it in a drop of water on the gla.s.s stage of the microscope.

Examine with one and one half inch power.[A]

Be careful to get just the focus. You are now ready to see the general form of the flower. At the base is a little body with roughened sides and slightly narrowed above (the ovary). Springing from the top of the ovary are a number of fine bristles (the pappus). Inside the bristles is a yellow portion, tubular below and flat above (the corolla).

Projecting from the tube of the corolla is a little yellow rod (the top of the stamens joined together); and coming from among the stamens are two slender recurved organs (the stigmas).

Now take a mounted needle in each hand and holding one needle on the flat part of the corolla split open the tubular part with the other. By keeping the lower part spread open with the needles, you will see that a number of delicate yellow threads grow from the sides of the corolla and are connected with the yellow stamen rod. These threads are another part of the stamens. In the middle of the flower is a single thread-like organ (the style) which comes from the top of the ovary and pa.s.sing through the stamens projects beyond them, divided into two stigmas.

Most of my readers have probably studied enough botany to know the names of the different parts of a flower, but very likely many of them do not recognize the parts of the Dandelion flower as looking anything like the parts of the flower with which they are familiar.

Before proceeding further, therefore let us take a Morning-Glory flower--which you all know and can easily obtain, or at least some flower like it--and let us see that the parts of the two correspond.

Commencing in the centre we find in both a pistil, consisting of an ovary at the base and a stigma at the top and a style between. In the Dandelion the stigma is split in halves, while in the morning-glory it is not split but has three little k.n.o.bs. Around the pistil come the stamens in each case. Each stamen is composed of two parts: a slender stem (the filament) and a little sac at the end (the anther) which is filled with pollen dust. In both cases the filaments grow out of the sides of the corolla. But while in the Morning-Glory the anthers are entirely free from one another, in the Dandelion they are joined together by their sides and form a tube around the style. The corolla in both cases is all of one piece, but in the Dandelion it is as if the upper part of the corolla were split open one side and then made flat.

Instead of a green calyx as in the Morning-Glory, the Dandelion has a number of delicate white bristles. And, finally, in the Morning-Glory both the calyx and corolla grow out from below the ovary, while in the Dandelion its calyx of bristles and its corolla issue from above the ovary. So after all, you will see that corresponding organs are in both, and the difference between the two flowers is not so great as one might think at first.

Let the different parts of the Dandelion be examined now more minutely.

First take some of the bristles and examine them with one quarter inch power. They are not perfectly smooth, but are more or less saw-like on the edge. With the same power look at other parts of the flower; notice the hairiness of the stigmas, the pollen grains coming out of the anthers (some grains may be found on the stigmas) also the roughness of the ovary and the delicate ribs or veins in the corolla. Examine one of the seed-like fruits with one and one half inch power. It is a ripened ovary. Compare the fruit with the ovary of a flower. The nutlet has become hard, rougher and more strongly ribbed. The narrowed upper part of the ovary has become much elongated and the pappus is spread out like an inverted umbrella.

Examine some bristles with one quarter inch power. They show the saw-like edges much more developed than in the younger bristles of the flower. We see throughout a beautiful adaptation of every part for fitting the little parachute to be carried long distances by the wind and finally to catch on some suitable place in which to sprout.

XIV.--HOW TO SEE A b.u.mBLE BEE.

You will first need to catch your b.u.mble Bee. A little chloroform poured on one will kill it instantly. Make a general examination at the outset of the insect. The outside of the body is h.o.r.n.y and covered thickly with hairs. On the upper side the hairs are much more numerous than on the under side. The whole body is divided into three regions: the head, bearing the feelers and mouth-parts; a middle part (thorax) bearing the four wings and six legs; and a hind part (abdomen) armed with the sting.

Remove the head and examine with one and one half inch power. At the sides are two prominent oval bodies (compound eyes) which seem to be crossed by five lines; near the top of the head, between the compound eyes, are three little s.h.i.+ny bead-like organs (simple eyes); starting from about the middle of the face are the two feelers (antennae) and at the lower part of the head are the mouth-parts. The sides, top and front of the head are all covered with hair.

Examine one of the compound eyes with one fourth inch power. The surface is made up of innumerable little facets, something like a cut diamond.

Cut off a piece of one of the compound eyes, remove some of the black pigment on the back and examine the piece in a drop of water. Each facet is a tiny hexagon. Some care is necessary to see them well.